
RANM(3F)            UNIX Programmer's Manual             RANM(3F)

NAME
     ranm, iran, rndmze, ransav, ranres - uniform pseudorandom
     number generator package

SYNOPSIS
     double precision function ranm()

     subroutine iran(i1, i2, i3, i4, i5, i6)
     integer*2 i1, i2, i3, i4, i5, i6

     subroutine rndmze

     subroutine ransav(ivec)
     integer*2 ivec(269)

     subroutine ranres(ivec)
     integer*2 ivec(269)

DESCRIPTION
     _R_a_n_m returns a uniform(0,1) pseudorandom double precision
     number.

     _I_r_a_n may be called with user specified arguments to initial-
     ize the generator.  Different inputs to _i_r_a_n result in dif-
     ferennt output sequences from _r_a_n_m.

     _R_n_d_m_z_e calls _i_r_a_n with unpredictable arguments.

     _R_a_n_s_a_v saves the entire current internal state of the gen-
     erator into the array _i_v_e_c.

     _R_a_n_r_e_s restores the entire internal state of the generator
     as previously saved by _r_a_n_s_a_v in the array _i_v_e_c.

     _I_r_a_n, _r_a_n_s_a_v or _r_a_n_r_e_s should not be used in the same pro-
     gram with _r_n_d_m_z_e.

ALGORITHM
     _R_a_n_m uses two linear congruential generators and a 64-entry
     shuffle table.

     On each call, two pseudorandom 31 bit integers are generated
     by the linear congruential method: N(i+1) = M * N(i) (mod P)
     where P = 2**31 - 1.  M = 7**13 (mod P) for one generator
     and 7**23 (mod P) for the other.  (The period of each linear
     congruential generator is 2**31 - 2.) The resulting 62 bits
     are used as follows: The first 56 bits form a pseudorandom
     double precision number in the interval [0,1).  The last 6
     bits determine a random address in the shuffle table
     (between 0 and 63) into which to insert the double precision
     number just formed.

Printed 7/31/83                                                 1

RANM(3F)            UNIX Programmer's Manual             RANM(3F)

     The internal state of _r_a_n_m is the contents of the two linear
     congruential seeds and of the shuffle table.

     On the first call _r_a_n_m generates 64 double precision numbers
     and inserts them (randomly, according to the above method)
     into the shuffle table.

SEE ALSO
     ranm(3M)

AUTHOR
     D. W. Hutchinson, David W. Krumme, J. Reeds, F. Rizzardi, D.
     M. Abrahams, Department of Statistics, U.C. Berkeley.

BUGS
     All six arguments to _i_r_a_n must be different to ensure a dif-
     ferent output sequence from _r_a_n_m.

Printed 7/31/83                                                 2